fix pic url

Author: wujunze

README_zh.md

@@ -49,7 +49,7 @@ typedef struct {
 ![image](https://wx3.sinaimg.cn/large/005LOzcmly1fgjes12fy5j30ya08qgn7.jpg)
 
 ## 编写Handler  模块真正干活儿的部分
-![image](https://ws2.sinaimg.cn/large/005LOzcmly1fgjfosnvf5j31hy0q6wlb.jpg
+![image](https://ws2.sinaimg.cn/large/005LOzcmly1fgjfosnvf5j31hy0q6wlb.jpg)
 
 ## 组合Nginx Module
 ![image](https://ws2.sinaimg.cn/large/005LOzcmly1fgjjo2l11jj31en0g4gq1.jpg)